Housing and method for making the same

ABSTRACT

A housing is provided which includes an aluminum or aluminum alloy substrate, an aluminum layer and a corrosion resistant layer formed on the aluminum or aluminum alloy substrate in that order. The corrosion resistant layer is an Al—C—N layer. Then, Ce ions are implanted in the Al—C—N layer by ion implantation process. The atomic percentages of N and C in the Al—C—N gradient layer gradually increase from the side of Al—C—N gradient layer near the aluminum or aluminum alloy substrate to the other side of Al—C—N gradient layer, away from aluminum or aluminum alloy substrate. Therefore the housing has a high corrosion resistance. A method for making the housing is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to co-pending U.S. patent application Ser.Nos. 13/213,437 13/220,856, 13/213,442, 13/220,861, 13/191,602,13/220,866, and 13/220,867 entitled “HOUSING AND METHOD FOR MAKING THESAME”. Such applications have the same assignee as the presentapplication. The above-identified applications are incorporated hereinby reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a housing and a method for making thesame.

2. Description of Related Art

Due to properties such as light weight and quick heat dissipation,aluminum and aluminum alloy are widely used in manufacturing components(such as housings) of electronic devices. Aluminum and aluminum alloyare usually anodized to form an oxide coating thereon to achieve adecorative and wear-resistant surface. However, the anodizing process iscomplicated and not very effective.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the exemplary process for surfacetreating aluminum or aluminum alloy and housings made of aluminum oraluminum alloy treated by the surface treatment. Moreover, in thedrawings like reference numerals designate corresponding partsthroughout the several views. Wherever possible, the same referencenumbers are used throughout the drawings to refer to the same or likeelements of an embodiment.

FIG. 1 illustrates a cross-sectional view of an exemplary embodiment ofa housing made of aluminum or aluminum alloy treated by present process.

FIG. 2 is a block diagram of an exemplary process for surface treatingaluminum or aluminum alloy

FIG. 3 is a schematic view of a PVD machine used in the present process.

FIG. 4 is a schematic view of an ion implantation machine used in thepresent process.

DETAILED DESCRIPTION

FIG. 1 shows a device housing 10 according to an exemplary embodiment.The device housing 10 includes an aluminum or aluminum alloy substrate11, aluminum layer 13 formed on the aluminum or aluminum alloy substrate11, and a corrosion resistant layer 15 formed on the aluminum layer 13.

The aluminum or aluminum alloy substrate 11 may be produced by punching.The corrosion resistant layer 15 is an Al—C—N gradient layer doped withCe ions implanted by the ion implantation process. The atomicpercentages of N and C in the Al—C—N gradient layer gradually increasefrom the side of Al—C—N gradient layer near the aluminum or aluminumalloy substrate to the other side of Al—C—N gradient layer, away fromaluminum or aluminum alloy substrate.

FIG. 3 shows a vacuum sputtering equipment 20, which includes a vacuumchamber 21 and a vacuum pump 30 connected to the vacuum chamber 21. Thevacuum pump 30 is used for evacuating the vacuum chamber 21. The vacuumchamber 21 has a number of aluminum targets 23 and a rotary rack (notshown) positioned therein. The rotary rack drives the aluminum oraluminum alloy substrate 11 to rotate along a circular path 25, and thesubstrate 11 also rotates on its own axis while rotating along thecircular path 25.

FIG. 2 shows an exemplary method for making the device housing 10, whichmay include:

The aluminum or aluminum alloy substrate 11 is pretreated. Thepre-treating process may include:

The aluminum or aluminum alloy substrate 11 is cleaned with alcoholsolution in an ultrasonic cleaner (not shown), to remove impurities suchas grease or dirt from the aluminum or aluminum alloy substrate 11.Then, the substrate 11 is dried.

The aluminum or aluminum alloy substrate 11 is plasma cleaned. Thealuminum or aluminum alloy substrate 11 is positioned in the rotary rackof the vacuum chamber 21. The vacuum chamber 21 is then evacuated toabout 3.0×10⁻⁸ Pa. Argon gas (abbreviated as Ar gas having a purity ofabout 99.999%) is used as sputtering gas and fed into the vacuum chamber21 at a flow rate of about 500 standard-state cubic centimeters perminute (sccm). The aluminum or aluminum alloy substrate 11 is appliedwith a negative bias voltage of about −100 volts (V) to about −180 V,then high-frequency voltage is produced in the vacuum chamber 21 and theAr gas is ionized into plasma. The plasma strikes the surface of thealuminum or aluminum alloy substrate 11 to clean the surface of thealuminum or aluminum alloy substrate 11. The plasma cleaning of thealuminum or aluminum alloy substrate 11 lasts about 3 minutes (min) toabout 10 min.

The aluminum layer 13 is vacuum sputtered on the pretreated an aluminumor aluminum substrate 11. In one exemplary embodiment, an aluminum layer13 is then formed on the aluminum or aluminum alloy substrate 11 byphysical vapor deposition (PVD). The formation of the aluminum layer 13uses argon gas as the sputtering gas. The flux of the argon being fromabout 100 sccm to about 300 sccm. During sputtering, the power of thealuminum targets being from about 2 kw to about 8 kw, and the aluminumor aluminum substrate 11 is applied with a negative bias voltage ofabout −300 V to about −500 V. The vacuum sputtering of the aluminumlayer takes about 5 min to about 10 min. The aluminum layer 13 has athickness of about 100 nm to about 300 nm.

The corrosion resistant layer 15 is formed on the aluminum layer 13. Thecorrosion resistant layer 15 is an Al—C—N gradient layer formed bymagnetron sputtering, and then the Al—C—N gradient layer is doped withCe ions by the ion implantation process. An exemplary magnetronsputtering process for forming the corrosion resistant layer 15includes: first, simultaneously applying argon, acetylene, and nitrogen,the flux of the argon being from about 100 sccm to about 300 sccm, theflux of the acetylene being from about 10 sccm to about 20 sccm, and theflux of the nitrogen is about 10 sccm to about 20 sccm; applying a biasvoltage to be substrate of about −150 V to about −500 V. During thisprocess, the flux of the nitrogen and acetylene flow rates are bothincreased about 10 sccm to about 20 sccm at a depositing interval ofabout every 10 min to about 15 min. The evaporation of the corrosionresistant layer 15 takes a total of about 30 min to about 90 min. Thecorrosion resistant layer 15 has a thickness of about 0.5 μm to about2.0 μm.

The formation process of the corrosion resistant layer 15 forms acompact Al—C—N solid phase, thus increasing the density of the corrosionresistant layer 15. Therefore, corrosion resistance of the devicehousing 10 can be improved.

The atomic percentages of N and C in the Al—C—N gradient layer graduallyincrease from the side of Al—C—N gradient layer near the aluminum oraluminum alloy substrate to the other side of Al—C—N gradient layer,away from the aluminum or aluminum alloy substrate. The gradient layercan decrease the mismatching of crystal lattices between the corrosionresistant layer 15 and aluminum layer 13. The formation of the aluminumlayer 13 between the aluminum or aluminum alloy substrate 11 and thecorrosion resistant layer 15 may improve the interface mismatch betweenthe aluminum or aluminum alloy substrate 11 and the corrosion resistantlayer 15, and can decrease residual stress in the corrosion resistantlayer 15. Thus the device housing 10 becomes less prone to stresscorrosion. The stress corrosion refers to the metal invalidityphenomenon under action of residual or applied stress and corrosivemedium. The device housing 10 has a high corrosion resistance.

Lastly, the corrosion resistant layer 15 is implanted with Ce ion. Theimplanted ions can fill pores of the corrosion resistant layer 15 toincrease the density of the corrosion resistant layer 15. Furthermore,the corrosion resistant layer 15 is a homogeneous amorphous film. Thus,the corrosion resistance of the aluminum or aluminum alloy substrate 11can be improved.

Ce is implanted in the corrosion resistant layer 15 by ion implantationprocess. In an exemplary embodiment, the ion implantation process isperformed by supplying a process gas containing Ce ion gasified fromcerium metal into a processing chamber 20 of an ion implantation machine100 as shown in FIG. 4. The machine 100 includes a plasma source 30coupled to a RF source power 32. Plasma is generated by applying the RFsource power 32 to dissociate ions from the process gas, thereby forminga source of ions that are accelerated toward and implanted into thesubstrate 11. The implanted ions react with the atoms and molecules ofthe surface layer of the substrate 11.

The ion implantation process may be performed under the followingconditions. The processing chamber 20 is evacuated to maintain apressure of about 1×10⁻⁴ Pa. The process gas supplied into theprocessing chamber 20 maintains a working atmosphere from about 0.1 Pato about 0.5 Pa. The RF source power 32 may be controlled from about 30kV to about 100 kV to form a beam of ions having an intensity of about 1milliampere (mA) to about 5 mA. The density of the ions implanted in theion implantation layer 13 may be from about 1×10¹⁶ ions per squarecentimeter (ions/cm²) to about 1×10¹⁸ ions/cm². The processing chamber20 may be maintained at a normal room temperature. The Ce metallurgicalbonds with the Al—C—N gradient layer by implantation, and forms theamorphous property. The structural characteristics of amorphous includesisotropic, no dislocation, and so on. Thus, the Al—C—N gradient layer isa homogeneous amorphous film. And, the corrosion resistance of thesubstrate 11 can be improved.

EXAMPLES

Experimental examples of the present disclosure are described asfollowing.

Example 1

The vacuum sputtering equipment 20 used in example 1 is a mediumfrequency magnetron sputtering equipment (model No. SM-1100H)manufactured by South Innovative Vacuum Technology Co., Ltd.

The substrate is made of aluminum.

Plasma cleaning: Ar gas is fed into the vacuum chamber 21 at a flow rateof about 280 sccm. The aluminum substrate 11 is applied with a negativebias voltage at −300 V. The plasma cleaning the aluminum substrate 11takes about 9 min.

Sputtering of the aluminum layer 13: Ar gas is fed into the vacuumchamber 21 at a flow rate of about 100 sccm. The power of the aluminumtargets 23 is 2 kw and the aluminum substrate 11 is applied with anegative bias voltage of −500 V. The depositing of the aluminum layer 13takes a total time of 5 min.

Sputtering of the Al—C—N gradient layer: Argon, acetylene, and nitrogenare simultaneously applied. The flux of the argon is about 100 sccm, theflux of the acetylene is about 10 sccm, and the flux of the nitrogen isabout 10 sccm. A bias voltage about −500 V is then applied to thesubstrate. Both the nitrogen and acetylene flow rates are each increasedabout 10 sccm about every 10 minutes and evaporate the aluminum targetat a power of about 5 kw. The depositing of the Al—C—N gradient layertakes a total time of 30 min.

Ion implanting Ce ions comprises: the processing chamber is evacuated tomaintain a pressure of about 1×10⁻⁴ Pa, the process gas maintains aworking atmosphere of about 0.1 Pa in the processing chamber. The RFsource power is at about 30 kV to form an ion beam with an intensity ofabout 1 mA. The density of the ions implanted in the ion implantationlayer is about 1×10¹⁶ ions/cm².

Example 2

The vacuum sputtering equipment 20 used in example 2 is a same inexample 1.

The substrate is made of 3003 type aluminum alloy.

Plasma cleaning: Ar gas is fed into the vacuum chamber 21 at a flow rateof about 230 sccm. The aluminum alloy substrate 11 is applied with anegative bias voltage at −480 V. The plasma cleaning the aluminum alloysubstrate 11 takes about 7 min.

Sputtering of the aluminum layer 13: Ar gas is fed into the vacuumchamber 21 at a flow rate of about 200 sccm. The power of the aluminumtargets 23 is 5 kw and the aluminum alloy substrate 11 is applied with anegative bias voltage of −400 V. The depositing of the aluminum layer 13takes a total time of 7 min.

Sputtering of the Al—C—N gradient layer: Argon, acetylene, and nitrogenare simultaneously applied, the flux of the argon is about 200 sccm, theflux of the acetylene is about 60 sccm and the flux of the nitrogen isabout 15 sccm; A bias voltage −300 V is then applied to the substrate.Both the nitrogen and acetylene flow rates increase about 15 sccm aboutevery 12 minutes and evaporate the aluminum target at a power of about 5kw. The depositing of the Al—C—N gradient layer takes a total time of 60min.

Ion implanting Ce ions comprises: The processing chamber is evacuated tomaintain a pressure of about 1×10⁻⁴ Pa, the process gas maintains aworking atmosphere of about 0.1 Pa in the processing chamber. The RFsource power is at about 60 kV to form an ion beam with an intensity ofabout 2 mA. The density of the ions implanted in the ion implantationlayer is about 1×10¹⁷ ions/cm².

Example 3

The vacuum sputtering equipment 20 used in example 3 is the same inexample 1.

The substrate 11 is made of 5252 type aluminum alloy.

Plasma cleaning: Ar is fed into the vacuum chamber 21 at a flow rate ofabout 160 sccm. The aluminum alloy substrate 11 is applied with anegative bias voltage at −400 V. The plasma cleaning the aluminum alloysubstrate 11 takes about 6 min.

Sputtering of the aluminum layer 13: Ar gas is fed into the vacuumchamber 21 at a flow rate of about 300 sccm. The power of the aluminumtargets 23 is 8 kw and the aluminum alloy substrate 11 is applied with anegative bias voltage of −300 V. The depositing of the aluminum layer 13takes a total time of 10 min.

Sputtering of the Al—C—N gradient layer: simultaneously applying argon,acetylene, and nitrogen, the flux of the argon is about 300 sccm, theflux of the acetylene being is 100 sccm, and the flux of the nitrogen isabout 20 sccm. A bias voltage about −150 V is then applied to thesubstrate; Both the nitrogen and acetylene flow rates increase about 20sccm about every 15 minutes and evaporate the aluminum target at a powerof about 5 kw. The depositing of the Al—C—N gradient layer takes a totaltime of about 90 min.

Ion implanting Ce ions comprises: The processing chamber is evacuated tomaintain a pressure of about 1×10⁻⁴ Pa, and the process gas maintains aworking atmosphere of about 0.1 Pa in the processing chamber. The RFsource power is at about 100 kV to form an ion beam with an intensity ofabout 5 mA. The density of the ions implanted in the ion implantationlayer is about 1×10¹⁸ ions/cm².

It is to be understood, however, that even through numerouscharacteristics and advantages of the exemplary disclosure have been setforth in the foregoing description, together with details of the systemand function of the disclosure, the disclosure is illustrative only, andchanges may be made in detail, especially in matters of shape, size, andarrangement of parts within the principles of the disclosure to the fullextent indicated by the broad general meaning of the terms in which theappended claims are expressed.

What is claimed is:
 1. A housing, comprising: a substrate made ofaluminum or aluminum alloy; an aluminum layer formed on the aluminum oraluminum alloy; a corrosion resistant layer formed on the aluminumlayer; wherein the corrosion resistant layer is an Al—C—N gradient layerdoped with Ce ions, the atomic percentages of N and C in the Al—C—Ngradient layer gradually increase from the side of Al—C—N gradient layernear the aluminum or aluminum alloy substrate to the other side ofAl—C—N gradient layer, away from aluminum or aluminum alloy substrate.2. The housing as claimed in claim 1, wherein the corrosion resistantlayer has a thickness of about 0.5 μm to about 2.0 μm.
 3. The housing asclaimed in claim 1, wherein the aluminum layer has a thickness of about100 nm to about 300 nm.
 4. A method for surface treating aluminum oraluminum alloy, the method comprising: providing a substrate made ofaluminum or aluminum alloy; forming an aluminum layer on the substrateby physical vapor deposition; forming a corrosion resistant layer formedon the aluminum layer, the corrosion resistant layer is an Al—C—Ngradient layer doped with Ce ions which is implanted by ion implantationprocess, the atomic percentages of N and C in the Al—C—N gradient layergradually increase from the side of Al—C—N gradient layer near thealuminum or aluminum alloy substrate to the other side of Al—C—Ngradient layer, away from aluminum or aluminum alloy substrate.
 5. Themethod as claim in claim 4, wherein the step of forming Al—C—N gradientlayer comprises: simultaneously applying argon, acetylene, and nitrogen,the flux of the argon being from about 100 sccm to about 300 sccm, theflux of the acetylene being from about 10 sccm to about 20 sccm and theflux of the nitrogen being from about 10 sccm to about 20 sccm; applyinga bias voltage to the substrate of about −150 V to about −500 V; theflux of the nitrogen and acetylene flow rates are both increased about10 sccm to about 20 sccm at a at a depositing interval of about every 10min to about 15 min. Evaporating the Al—C—N gradient layer taking atotal time of about 30 min to about 90 min.
 6. The method as claim inclaim 4, wherein, ion implanting Ce ions comprises: evacuating theprocessing chamber to maintain a pressure of about 1×10⁻⁴ Pa, theprocess gas maintains a working atmosphere from about 0.1 Pa to about0.5 Pa in the processing chamber.
 7. The method as claim in claim 6,wherein the step of ion implanting Ce ions further comprises supplying aRF source power to dissociate the ions from the process gas.
 8. Themethod as claim in claim 6, wherein the RF source power is controlledfrom about 30 kV to about 100 kV to form a beam of the ions with anintensity from about 1 mA to about 5 mA.
 9. The method as claimed inclaim 6, wherein the density of the ions implanted in the ionimplantation layer is of about 1×10¹⁶ ions/cm² to about 1×10¹⁸ ions/cm².10. The method as claimed in claim 6, wherein the step of forming thealuminum layer comprises: using argon gas as sputtering gas, the flux ofthe argon being from about 100 sccm to about 300 sccm, the power of thealuminum targets is of about 2 kw to about 8 kw, the substrate isapplied with a negative bias voltage is of about −300 V to about −500 V,vacuum sputtering the aluminum layer takes about 5 min to about 10 min.11. The method as claim in claim 4, wherein the method further comprisespolishing and ultrasonically cleaning the aluminum or aluminum alloysubstrate before forming the aluminum layer.